JP2003161710A - Energy dispersion type semiconductor x-ray detector - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an energy dispersion type semiconductor X-ray detector that can detect a desired characterized X-ray with accuracy, by avoiding the bad influence of a system peak generated when an electron beam projected to a sample collides with a lower pole piece positioned below the sample after passing through the sample when the sample has a thin film-like shape. <P>SOLUTION: In this semiconductor X-ray detector 8 constituted to detect the characteristic X-ray 9 generated in the sample 5 positioned between an upper pole piece 6 and the lower pole piece 7 when the electron beam 3 emitted from an electron beam source 1 is projected upon the sample 5 from the upside of the sample 5, a collimator 12 provided with a system peak incidence blocking section 16 which blocks the incidence of the system peak 15 generated when the electron beam 3 collides with the lower pole piece 7 is provided in front of an X-ray transmitting window 11. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an energy dispersive semiconductor X-ray detector used in combination with, for example, a scanning electron microscope.

[0002]

2. Description of the Related Art A scanning electron microscope (hereinafter referred to as SEM) is one of energy dispersive X-ray microanalyzers.
And an energy dispersive X-ray analyzer (hereinafter referred to as EDX) that processes signals from a semiconductor X-ray detector attached to this SEM. Such an energy dispersive X-ray microanalyzer is an apparatus for elemental analysis of a minute region of several μm.
Since it is possible to perform "qualitative analysis", "quantitative analysis", "analysis of element distribution by X-ray image", etc. of the portion being observed by EDX simultaneously with image observation by SEM, metal, ceramic, It is used for research on materials such as semiconductors, but in recent years, it has also come to be used in the field of quality control such as trouble analysis of products.

By the way, in the conventional energy dispersive X-ray microanalyzer, when performing the above-mentioned analysis, an analysis point is set, and the set point is irradiated with an electron beam by SEM, and the characteristics obtained at that time are obtained. X-rays are detected by an energy dispersive semiconductor X-ray detector (hereinafter, simply referred to as X-ray detector).

By the way, S combined with the conventional EDX
In the EM, as shown in FIG. 5, the X-ray detector 41 is arranged above the sample 42, and the upper surface 42 a of the sample 42 is
The characteristic X-ray 44 generated in the sample 42 when the sample 4 is irradiated with the electron beam 43 is detected by the X-ray detector 41,
Two surface and / or inside information were obtained. In FIG. 5, 41a is an X-ray transmission window, 41b
Is an X-ray detection element, and 41c is a low noise FET unit that takes out the output of the X-ray detection element 41b. Reference numeral 45 is a collimator for preventing the incidence of scattered X-rays and the like, and
Is an upper pole piece and a lower pole piece for converging and scanning the electron beam 43 irradiated toward the sample 42.

[0005]

However, like the SEM having the above structure, the sample 42 is an in-lens type that holds the sample 42 between the upper and lower pole pieces 46 and 47, and the X-ray detector 41 is used as the sample. When the sample 42 is a thin film, the lower pole piece 4 in which the electron beam 43 is located below the sample 42 is arranged above the sample 42.
7, the system peak 48 generated therein may enter the X-ray detection element 41b of the X-ray detector 41, and this system peak 48 becomes noise in the detection of the characteristic X-ray 44 from the sample 42. Sample 42
Is a bulk sample having a certain thickness in the electron beam irradiation direction, or an SEM without the lower pole piece 47, the above problem does not occur.

The present invention has been made in consideration of the above matters, and an object thereof is that when a sample is a thin film, the electron beam irradiated to this sample passes through the sample and the lower part thereof is passed. It is an object of the present invention to provide an X-ray detector capable of accurately detecting a desired characteristic X-ray without being adversely affected by a system peak generated by colliding with a lower pole piece located at.

[0007]

In order to achieve the above object, the invention according to claim 1 relates to a sample in which an electron beam from an electron beam source is provided between an upper pole piece and a lower pole piece. In the energy dispersive semiconductor X-ray detector, the characteristic X-rays generated in the sample when irradiated by the above are detected from above the sample. It is characterized in that a collimator is provided with a system peak incidence blocking unit for blocking the incidence of the system peak that occurs when the vehicle collides with.

Further, in order to achieve the above-mentioned object, claim 2
According to the invention described in (1), characteristic X-rays generated in the sample when the electron beam from the electron beam source is irradiated to the sample provided between the upper pole piece and the lower pole piece from above the sample. In the energy dispersive semiconductor X-ray detector for detection, an X-ray detection element is provided at a position where a system peak generated when the electron beam collides with the lower pole piece does not enter.

In any of the above-mentioned inventions, in the X-ray analysis of a thin film sample, the system peak generated when the electron beam transmitted through the sample collides with the lower pole piece is completely incident on the X-ray detecting element. The desired characteristic X-rays can be detected with high accuracy, and X-rays of thin film samples can be detected.
Line analysis can be performed with high accuracy.

[0010]

DETAILED DESCRIPTION OF THE INVENTION The details of the present invention will be described below with reference to the drawings. 1 and 2 show a first embodiment of the present invention. FIG. 1 schematically shows an example of the configuration of an optical portion of an SEM incorporating the X-ray detector of the present invention. 2 schematically shows an example of the configuration of the main part.

First, in FIG. 1, 1 is a sample chamber 2 made of iron.
Is an electron beam source provided above the inside of, and is composed of, for example, an electron gun, and emits an electron beam 3 downward. Reference numeral 4 is a sample holder for mounting and holding the sample 5, and an upper pole piece 6 and a lower pole piece 7 for focusing the electron beam 3 on the sample 5 are provided obliquely above and below the sample holder, respectively.
Is provided and is configured as a so-called in-lens system. Reference numeral 8 denotes an X-ray detector, which is provided above the upper surface of the sample 5 and is used when the sample 5 is irradiated with the electron beam 3.
The characteristic X-rays 8 generated on the upper surface of are detected.

FIG. 2 (A) is an enlarged view showing the vicinity of the X-ray detector 8. In FIG. 2 (A), 10 is an end cap, and one end thereof is made of, for example, beryllium foil. An X-ray transmission window 11 is formed so as to be directed obliquely downward, and an X-ray detection element 12 made of, for example, a high-purity Si wafer and a low-noise FE for extracting its output are formed inside the X-ray transmission window 11.
A T unit 13 is provided. A collimator 14 for preventing the incidence of scattered X-rays and the like is provided outside the X-ray transmission window 11. Although not shown, the other end of the end cap 10 is thermally coupled to a cold heat section such as liquid nitrogen, so that the X-ray detection element 12 and the low noise FET unit 13 are in a predetermined low temperature state. Is configured. Further, the low noise FET unit 13 is connected to an external signal processing section by a signal line (not shown).

In this embodiment, the collimator 14 has the electron beam 3 on the front side (the incident side of the characteristic X-ray 9) and the lower pole, as can be understood from FIG. 2B. A system peak incidence blocking portion 16 for blocking the incidence of the system peak 15 that occurs when the piece 7 collides with the piece 7 is formed. More specifically, the peripheral portion of the lower end side of the X-ray transmission hole 14a of the collimator 14 closer to the sample 5 is moved upward so as not to prevent the characteristic X-ray 9 from entering the X-ray detection element 12 as much as possible. A projection is provided so as to protrude to the system peak incidence blocking section 16. It goes without saying that the upward projection length and shape of the system peak incidence blocking portion 16 should be set in a range that does not reduce the detection sensitivity of the characteristic X-ray 9 as much as possible.

In the SEM having the above structure, when the thin film sample 5 is subjected to X-ray analysis, the sample 5 is set in the sample holder 4 and the sample 5 is irradiated with the electron beam 3 from the electron beam source 1. Due to this irradiation, the characteristic X-rays 9
The characteristic X-ray 9 enters the X-ray detection element 12 through the collimator 14 and the X-ray transmission window 11. With this incidence, a signal is output from the low noise FET unit 13, this output signal is appropriately processed, and the X-ray spectrum of the sample 5 is obtained.

In this case, a part of the electron beam 3 irradiating the sample 5 passes through the sample 5 and collides with the lower pole piece 7 below, and this collision produces a system peak 15, which is an X-ray detector. Go to 8. However, X of the X-ray detector 8
In the collimator 14 mounted on the front surface of the line transmission window 11,
Since the system peak incidence blocking unit 16 is provided,
The system peak 15 is blocked by the system peak incidence blocking unit 16 and does not enter the X-ray detection element 12. Therefore, the X-ray detector 8 can detect a desired characteristic X-ray with high accuracy without being affected by the system peak 15.

According to the above construction, the X-ray detector 8
The angle (effective angle) with respect to the sample 5 can be secured.

In the first embodiment, the peripheral portion of the X-ray transmission hole 14a of the collimator 14 on the lower end side closer to the sample 5 allows the characteristic X-ray 9 to be incident on the X-ray detection element 12. It was formed on the system peak incidence blocking portion 16 by projecting upward so as not to interfere with the above. However, instead of this,
As in the second embodiment shown in FIG. 3, the system peak incidence blocking portion 16A is provided so as to project from the end on the lower end side closer to the sample 5 of the X-ray transmission hole 14a of the collimator 14 to the front (sample 5 side). May be. In this case, the projection degree, the projection angle, and the shape of the system peak incidence blocking portion 16A are
It should be said that the detection sensitivity of the characteristic X-ray 9 should be set within a range that does not decrease as much as possible, and that it should be set in consideration of not contacting the sample 5 or the sample holder 4. There is no end. Note that FIG. 3 shows an example in which the system peak incidence blocking portion 16A is provided so as to protrude horizontally forward from the end portion on the lower end side.

Since the operation and effect of the second embodiment are the same as those of the first embodiment,
The description is omitted.

In the above-described first and second embodiments, the system peak incidence blocking section 16 or 16A is formed in the collimator 14 in order to block the system peak 15 from entering the X-ray detecting element 12. However, the X-ray detection element 12 may be provided at a position far from the X-ray transmission window 11 so that the system peak 15 does not enter.

That is, FIG. 4 shows a third embodiment of the present invention. As shown in this figure, in the X-ray detecting element 12, the system peak 15 passes through the X-ray transmission window 11 and the X-ray is transmitted. The X-ray transmission window 11 in the end cap 10 is arranged so that the light does not enter the X-ray detection element 12 even if it enters the detector 9.
It is provided at a position further away from, that is, at a position away from (retracted from) the X-ray transmission window 11. Even in this case, when setting the position of the X-ray detection element 12,
It goes without saying that the detection sensitivity of the characteristic X-ray 9 should be taken into consideration.

[0021]

As described above, according to the present invention, when performing X-ray analysis of a thin film sample, the X-ray of the system peak generated when the electron beam transmitted through the sample collides with the lower pole piece. It is possible to completely prevent the light from entering the detection element. Therefore, the desired characteristic X-ray can be detected with high accuracy, and the thin film sample can be analyzed with high accuracy.

[Brief description of drawings]

FIG. 1 is a diagram schematically showing an example of the configuration of an optical portion of a scanning electron microscope incorporating the X-ray detector of the present invention.

FIG. 2 is an enlarged view showing a configuration of a main part of the optical portion.

FIG. 3 is a diagram schematically showing another example of the configuration of the optical part of the scanning electron microscope incorporating the X-ray detector of the present invention.

FIG. 4 is a diagram schematically showing still another example of the configuration of the optical portion of the scanning electron microscope incorporating the X-ray detector of the present invention.

FIG. 5 is a diagram for explaining a conventional technique.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Electron beam source, 3 ... Electron beam, 5 ... Sample, 6 ... Upper pole piece, 7 ... Lower pole piece, 8 ... X-ray detector, 9 ...
Characteristic X-ray, 11 ... X-ray transmission window, 12 ... Collimator, 15
... System peak, 16, 16A ... System peak incidence blocking unit.

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2G001 AA03 BA05 CA01 DA01 DA03                       GA01 GA06 KA01 MA05 SA02                       SA04                 2G088 EE30 FF03 FF15 GG21 JJ01                       JJ09 JJ12 JJ24 JJ29 LL02

Claims (2)

[Claims] 1. A characteristic X-ray generated in a sample when an electron beam from an electron beam source is applied to a sample provided between an upper pole piece and a lower pole piece is detected from above the sample. In the energy dispersive semiconductor X-ray detector configured as described above, a system peak incidence blocking unit for blocking incidence of a system peak generated when the electron beam collides with the lower pole piece on the front surface of the X-ray transmission window. An energy dispersive semiconductor X-ray detector characterized in that a collimator provided with is provided. 2. A characteristic X-ray generated in the sample when the sample provided between the upper pole piece and the lower pole piece is irradiated with the electron beam from the electron beam source, is detected from above the sample. In the energy dispersive semiconductor X-ray detector configured as described above, an X-ray detection element is provided at a position where a system peak generated when the electron beam collides with the lower pole piece does not enter. Semiconductor X-ray detector.